Electrical time switch



Nov. 15, 1949 Filed April 30, 1948 W. J. AETKEN ELECTRICAL TIME SWITCH 3 Sheets-Sheet 1 IN VE/V TOE.

1949 w. J. AITKEN ELECTRICAL TIME SWITCH 3 Sheets-Sheet 2 Filed April 30, 1948 INVENTOR W. J. AITKEN Nov. i5, 1949 ELECTRICAL TIME SWITCH 3 Sheets-Sheet 3 Filed April 30, 1948 Pat ented Nov. 15, 1949 UNITED STATES PATENT OFFICE ELECTRICAL TIME SWITCH William J. Aitken, Manitowoc, Wis. Application April 30, 1948, Serial No. 24,242 Claims. (01. 200-38) There are various kinds of motor-driven automatic switches adapted to open and close electric circuits at predetermined times during a predetermined period of time, say each twenty-four hour day; the cycle being repeated as long as the operating motor continues to run.

The present invention has for its object to produce a switch of the aforesaid general type that shall be simple and novel in construction, that shall be highly efficient and reliable in operation over long periods of time without needing attention and that can very easily and quickly be adjusted to achieve any desired timing cycles.

Another object of the invention is to provide an automatic electric timing device including a synchronous-electric-motor-driven timing mechanism comprising a plurality of tripper-armactuated triangular timing wheels cooperating with a pair of coaxially mounted switch actuating cams; the cams and switches being so constructed and so arranged that the circuit controlled by said switches is closed and opened at predetermined intervals of time with snap action to thereby obviate arcing between the switch contacts.

Another object of the invention is found in the provision of manually operable means permitting manual operation of the switches into either closed or open position at any desired time without altering any automatic preset sequence of switch operation.

Another object of the invention resides in the provision of novel means for latching the switchactuating tripper arms to a time-graduated dial plate which is driven by a synchronous electric motor including a novel frictional mounting for the pivotal ends of the tripper arms whereby the tripper arms may readily be manually adjusted relatively to one another and to the dial plate without disconnecting the dial plate from its operative connection with the motor.

The Various features of novelty whereby the present invention is characterized will hereinafter be pointed out with particularity in the claims, but, for a full understanding of the invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawings wherein:

Fig. 1 is a front view of a switch embodying my invention in a preferred form, removed from its casing; Fig. 2 is a side view of the switch viewed from a point to the right of Fig. 1; Fig. 3 is a rear view of the switch; Fig. 4 is a section on line 4-4 of Fig. 2 showing the indexing device; Fig. 5 is a section on line 5-5 of Fig. 4; Fig. 6 is a section on line 65 of Fig. 2, only the cam shaft and the tripper-arm-actuated triangular timing wheels thereon being shown; Fig. '7 is a section on line l-'! of Fig. 1, only the cam shaft and the parts contiguous thereto being shown; Fig. 8 is a view of the rear or underside of the dial unit; Fig. 9 is a View of the switch operating mechanism looking at the opposite side of the switch from that which is presented to the observer in Fig. 2; Fig. 10 is a section on line I0I0 of Fig. 9; and Figs. 11 and 12 are sections on an enlarged scale taken, respectively, on lines ll-l I and I 2-]2 of Fig. 1.

Referring to the drawings, I5 is a plate composed of tough insulating material, which may be of the phenolic resin type. On the rear side of this plate is an electric motor [6 provided with a dust-proof gear casing I! that fits snugly against and is fastened to the plate [5. Also on the rear side of the plate 15 are a plurality of terminals, four of them, 18, I 9, 20 and 2 I, being shown; these terminals being arranged at one end of the plate and projecting beyond the same. The motor is connected directly to terminals [8 and I9 so that, whenever these two terminals are connected to an energized outside circuit, the motor runs. Terminals 20 and 2i are for connection with the translating device that is to be energized intermittently; and, in order alternately to connect and disconnect terminals 20 and 2! to terminals [8 and 19, I provide two switches 25 and 26.

Switch 25 comprises a contact piece 2! on terminal I8 and a cooperating contact piece 28 fixed on one end of a spring arm or blade 29, while the other end of such arm or blade is anchored to terminal 20. Switch 26 comprises a contact piece 30 mounted on terminal I 9 and a second, cooperating contact piece 3! on a spring arm or blade 32 that is anchored to terminal 2|. The terminals are L-shaped, their shorter arms 18 19 20 and 2 I projecting rearwardly from and at right angles to plate I5; arms 15 and 20 being longer than the other two, so that switch 25 is farther away from the supporting plate than is switch 26.

The means for operating the switches is a cam shaft 34 mounted on plate l5 not far from the contact-bearing ends of the switch members; the shaft extending through the plate at right angles thereto and projecting forwardly and rearwardly therefrom. Fixed to the rearwardly projecting part of the cam shaft, in the same planes parallel to the supporting plate that contain the longitudinal center lines of switch arms 29 and 32, respectively, are two switch-actuating cams 35 and 36 composed of suitable insulating material. These two cams are alike, each being preferably shown in the form of a pair of thick discs having a plurality of excisions in its edge, obviously each cam could comprise a single disc of thick insulating material. Because I have selected for the sake of illustration a timer that opens and closes a circuit at least three times, during each revolution of the cam shaft 34, each cam has three V-shaped excisions; one side 31 of each excision being approximately radial while the other side 38 makes an obtuse angle therewith. The excisions in the two cams register with each other axially of the cam shaft.

Switch arm 29 has thereon a finger 39 that lies in the plane of and reaches over to cam-35,. Arm or blade 32 has at its free end anextension 40 constituting a finger that extends into proximity to cam 36. The parts are so proportioned that these two fingers at all times occupy similar positions relatively to the corresponding cams. Also, each switch arm is constantly under stress so that the contact piece thereon is firmly pressed against the cooperating stationary contact, when not restrained by its actuating cam.

As will hereinafter be explained, the cam shaft 34 is driven step by step in the counter-clockwise direction as viewed in Fig. 3. When the fingers are riding on the unmutilated portions of the cams, as in Fig. 3, the switches are open. Then, upon turning the cam shaft until the nearest excisions in the cams reach the fingers, the fingers drop abruptly into those excisions and both switches close with a snap action. The excisions are so long and so deep that the switches may thereafter open with asnap action, even though the fingers 391V and do are required to ride up a gradual slope. This is for the reason that whenever the cam shaft has been turned half way through an angular distance of 60, it is driven sharply the rest of the way by a powerful indexing device.

The indexing device, as best shown in Figs. 4 and. 5, comprises a six pointed star wheel 4|, fixed to the, cam shaft in front of and near plate I5. Cooperating with this wheel is a plunger 42 that has a wedgershaped end 23 that fits into the \(f-shaped recess between any two consecutive points on the wheel. The plunger is provided with a stem 34 mounted in a suitable bracket 45, fixed to plate 15, for sliding movements radially of the cam shaft. A spring 46, surrounding the stem and bearing at one end against the plunger proper and at its other end against a part of the bracket, presses the plunger strongly against the star wheel. With the parts in the. positions occupied by them'in Fig. 4, a turning movement of the cam shaft results in forcing the plunger out of the. recess in which it is seated. When the tip of one of the star wheel points reaches and passes a little beyond the sharp. edge of the wedge, the spring rapidly forces the. wedge. against the trailing edge of that star wheel point and sharply drives the star wheel ahead.

The cam shaft is given a turning impetus at predetermined intervals by means driven. by mo-' tor l6 and acting through two triangular timing wheels fixed to that part of the cam shaft that projects forwardly from the supporting plate I5. These timing wheels consist of a triangular metal. plate i8 and a somewhat larger triangular plate. 49. These timing wheels 68v and 49, are fixed to the cam shaft 3 3 in spaced relation to each other, with the larger wheel 59 disposed nearer to the supporting plate; the timing Wheels being displaced 60 angularly of the shaft relatively to each other. Each edge of the timing wheel 48 contains a small depression 50, so located that there is a single depression at each apex or tip. At each tip of the timing wheel .9 is a little finger or projecting tip 5i. On the outer end of the cam shaft 35 is a knob 52 which may be used for manually turning the shaft 3 3, whereas the inner end of the shaft 35 extends through a stationary bearing element 53 for the purpose of steadying the shaft 34.

The actuator or means for actuating the switches through the cam shaft 34 and its 00-' operating timing wheels 48 and 59 includes elem'ents carried by a motor driven circular dial .54; these elements being adjustable on the dial independently of each other. I prefer to employ as such elements arms which are pivotally mounted on and disposed radially of the dial; each arm having thereon a pin adapted to engage one of the timing wheels once during each revolution of the dial 54. A satisfactory arrangement is one having two arms, one to-close-and the other to open the switches, but a greater number may-be used when desired.

In the arrangement shown, as best seen in Fig. '10, a shaft 55, driven by the motor i'8, extends forwardly through supporting plate [5 and there terminates in a screw-threaded section 56 A nut 5'1 is screwed down as far as it will go on the shaft. Overlying this nut 51 is a detachable unit comprising the dial 5d and the two cooperating arms 58 and 59. These three members are fas-v tened together by means of a device in the nature of a tubular rivet adapted to be slipped over the threaded end of the shaft. This fastening device comprises a disc-like head '60 a stem portiontl of somewhat smaller diameter and of a length substantially equal to the combined thic I;-, nesses of the arms; and a short stern continuation iiZ. of still smaller diameter. The arms con tain holes for the reception of part 61. of the fastener, while the dial has a central hole just large enough to receive the part 62 while rest: ing ontheshoulder at the juncture of parts GI. and 62 with each other. When the meld part 62 isjheaded over, as shown, the arms 58 and 5,9, and the dial are frictionally fastened together without clamping the arms so tightly that they cannot easily be manually adjusted relatively to each other and to the dial. After the unit just described is slipped onto the screw-threaded section of the shaft it then may be secured in place by means of ahut 63 screwed onto thes'haft 55, thus fastening the dial E l. to. the shaftv 55. a manner tocompei itto rotate with the same but still permitting adjustment of thearms 5.8 andZS. relatively to each other and to the, dial 5 i.

Each of the armsv 58 and. projects somewhat beyond the peripheryof the dial 54. and is there. blanked and formed to provide first, little prongs respectively 6 and 55 that are bent over the edge of the dial and. inwardly close tothe. dialface to limit the inward movements of the arms-When moved, into unlatched positions; and, second, lit tle finger pieces with jpointers respectively 65, and 51f that extend outwardly well'beyondI the periphery of the dial 5% and with theirQpointers 6t and 67' pointing toward suitable time-designat; ing. indicia .or graduations arranged circularly and,ne ar the periphery of the dial.

The dial contains small holes S8,;arnanged-in a circie. having a diameter only, a little l ess} than that of the dial; thusbringing these holesclose e iie f. t dial W en medial. s g atin- 75, aur ra a ridd' f WQnW-four hoursas hnwm the distance between the graduations of consecutive holes may conveniently represent fifteen minutes. Any other desired time designating indicia or graduations may be used to fit any desired operating conditions.

The arms 58 and 59 are latched in their positions of adjustment by pins thereon that enter the small holes 68 in the dial. When making the blanks for the arms each is provided with a hole 69 that is adapted to register consecutively with the small holes 58 in the dial as the arm is turned. Another hole 1D is also formed in each of the finger piece portions respectively 66 and 61.

In making up arm 58, a headed pin H is pressed into hole 69, as shown in Fig. 11, from the underside, and is caused to project far enough on the side next to the dial to permit it to enter any one of the holes 68 in the dial with which it may register. The arms are made of spring metal and tend constantly to lie fiat against the dial. A heavier pin 12 has a reduced end which extends through hole and is riveted to arm 58; this pin being the medium through which arm 58 actuates the timing wheel 48, as will further be explained. In making up arm 59, a pin 13 similar to pin 12, but much longer and having at one end a section 14 of small diameter, is securely driven into the hole 69 of arm 59 and is used to serve the functions of both pins H and 12; part 14 being adapted to extend up through any one of the holes 68 for the purpose of interlocking the arm 59 with the dial. The hole 19 in arm 59 is not used.

It will be understood that the parts are so proportioned and arranged that the cam shaft 34, shaft 55 that carries the dial, and pins ll, 12 and T3 are all parallel to each other, pin 12 being adapted to securely engage within depression 59 with what may be termed one tooth of the small timing wheel 48 whenever that pin is carried around to about a plane containing the axes of both of these shafts, while the switches are open and such tooth is the one nearest the dial as in Fig. 1. Pin 12 is too short, however, to engage the large timing wheel 49. Pin 13 is too close to the axis of rotation of the dial to engage timing wheel 48, but its length enables it to engage a tooth on the larger timing wheel 49 when the switches are closed and the cam shafthas been turned in the clockwise direction through an angle of 60 from the position that it occupies in Fig. 1.

In order that the dial may be used actually to indicate the time of day I provide a stationary pointer in the form of a bracket mounted on the front side of the supporting plate I5 and extending beyond the plane of the dial and then laterally over the marginal portion of the face of the dial.

The operation of the apparatus has been to some extent explained along with the description of the structural features. Briefly stated, however, when the particular time switch apparatus shown is to be operated so as to close a circuit at a predetermined time of day and to open it again at a second predetermined time; the finger piece 66 and arm 58 is pressed back to unlatch the arm, which is then turned to bring the pointer 66 in registration with one of the holes 68 on the dial representing the hour at which the switches are to be closed and when the arm 58 is released its pin H will enter the hole 68 and latch the arm to the dial. The same procedure is followed with the circuit-opening arm 59 to setit at the hour for again opening the switches: if the cam shaft is not already in one of its three switch-open positions such as shown in Fig. l, knob 52 is turned in the clockwise direction until the switches are open; care being taken that the arms are so set that as the dial turns, the circuit-closing arm 58 moves up to the tripper-arm-actuated timing wheels ahead of circuit-opening arm '59. After arm 59 has through the engagement of its pin '12 with the timing wheel 48 turned the cam shaft through an angle of 30, the indexing device is released into action and forcibly quickly rotates the shaft 34 through a furtherlike angle and holds it there. Now, however, one of the teeth on the larger timing wheel 49 lies in the path of the long pin 13 on arm 59 so that, at the proper time as the rotation of dial 54 is advanced, arm 59, acting on the larger timing wheel 49 will cause a rotation of the cam shaft until the indexing device again acts to complete this particular step in the turning movement of the cam shaft; the snap action in this instance being important since, otherwise, the switches might open so slowly as to cause objectionable sparking.

It should be noted that the manually operable switch trip knob 52 permits manual operation of the switches at any time, if so desired, without altering any automatic preset sequence of switch operation.

While I have illustrated and described with particularity only a single preferred form of my invention, I do not desire to be limited to the exact details thus illustrated and described, but intend to cover all forms and arrangements that come with the definitions of my invention constituting the appended claims.

1. In an automatic electrical time switch, a switch having an arm movable to open and close a circuit, a rotable shaft having thereon a cam adapted to engage said switch arm and move it, a pair of triangular timing wheels of different diameters fixed to said shaft in spaced relations lengthwise of the shaft, an actuator for said timing wheels rotatable about an axis parallel to said shaft and in a plane close to the plane of the smaller one of said timing wheels, two pins of relatively different lengths on the actuator paralleling said shaft, one of the pins being long enough to intersect the plane of the larger one of said timing wheels and the other being too short to reach that plane but long enough to intersect the plane of the smaller one of said timing wheels, the radial distances of the pins from the axis of the actuator being such that the short pin is adapted to operatively engage the smaller one of said timing wheels while the longer one of said pins reaches only to the larger one of said timing wheels.

2. In an automatic electrical time switch, a switch-operating cam shaft, a motor driven shaft parallel to the cam shaft and having thereon a time-designating dial disposed in a plane at right angles to the shafts, two timing wheels fixed to the cam shaft in planes paralleling that of the dial and spaced apart from each other, the timing wheel nearest the plane of the dial being smaller in diameter than the other, two pins adjustably mounted on the dial and paralleling said shafts, one pin being long enough to intersect the plane of the larger timing wheel and the other pin being only long enough to intersect the plane of the smaller timing wheel, and the long pin being at such a distance from the cam shaft, when nearest the same, that it cannot enpinis- .soilocated:thatitcan engage with said smaller timing wheel;

v3. Anautomatic electrical time switch as set forth claim ,2; wherein said time wheels are oftriangular form and are relatively displaced 60 with respect'to eachother, Vangularly of the cam shaft.

l. An automatic electrical time switch as set forth in claim 12, wherein each timing wheelis provided with the same number of pin-engaging projections, and wherein the timing wheels. are so displaced angularly with respect to each other that the turning of each timing wheel by the corresponding pin places the other timing wheel imposition to Ice/engaged by the pin corresponding thereto.

'5. An, automatic electrical time switch as set forth in claim 2 having, in additioman indexing star wheel on; the; cam shafts -.-together with .a

spring-pressed uwedgeeshaped ,dog cooperating with said mdexingwheelto snap. it from one-no.- sitionztoithe next aiter one of; thepins on the dial has rotated one ofutheqtiming wheels a predetermined angular, distance. WILLIAM J. AITKEN.

I 'REFERENCES CITED The following references are of record inthe fileof thispatent:

UNITED STATES PATENTS Number Name Date 15 1307.9;79'1 .Morden et al Nov. 25, 1913 1,551,894 'McGlyIm Sept 1, 1925 2,204,949 Riche IJune'1 8, 1940 2,243,566 Kimball -a May 27, I941 

